Heating or cooling people rather than buildings can save a lot of energy. A California non-profit, together with researchers from Stanford and UCLA, is developing footwear that will keep people comfortable in unsuitable environments. The ReBOOT system uses a low-voltage battery that powers a pump that moves water through a shoe insert made of thermally conductive materials to manage heat transfer from the soles of the feet and fans that keep the water at room temperature, even as the body tries to heat the water to body temperature. Research shows that wearables that heat or cool the feet can heat or cool the body ten times faster than standard devices such as cooling vests or thermal blankets.